This application claims the priority of German Application No. 101 13 638.2, filed Mar. 21, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a device for noise configuration in a motor vehicle.
Thanks to advances in acoustic technologies, motor vehicles of recent design, in particular vehicles of the sophisticated and sportscar class, are distinguished by high noise comfort in the passenger space of the vehicle. The high noise comfort is in this case characterized by a low sound-pressure level and by largely suppressed disturbing noises. This also applies to the external noise of the motor vehicle, in particular with regard to statutory regulations, according to which, for example in the Federal Republic of Germany, a maximum sound-pressure level of 74 dB(A) is prescribed.
The increasing emotional factor in the use of or decision to buy the above-mentioned vehicles results in the growing importance of a configuration of the internal and external noise of the motor vehicle which is aimed specifically at the particular type of vehicle.
Since vehicles of the luxury and sportscar class have a low sound-pressure level in the interior, it is often relatively difficult for the driver, solely by means of the engine noise prevailing in the interior of the vehicle, to detect the instantaneous load state of the internal combustion engine arranged in the vehicle. However, this is frequently desirable, precisely in the sportscar sector, because it is precisely here where there are vehicles in which the driver""s subjective impressions play a part in the use or purchase of such a vehicle.
In order nevertheless to afford the driver the possibility of detecting the load state of the engine during travel by means of the engine noise, measures are taken on the sound insulation system, and this may mean an increase in the external noise level. This often results in appreciable pollution of the adjacent surroundings or of the environment. Furthermore, because of statutory provisions, the external noise level can be increased only to a very restricted extent.
The problems described above have already been recognized, and it is known from German Patent Document DE 197 04 376 A1 to connect the filter housing of an air-filter arrangement for an internal combustion engine of a motor vehicle acoustically to the passenger space of the motor vehicle via a line.
DE 42 33 252 C1 describes a motor vehicle in which a main line of an intake or exhaust system is connected to the passenger space via a line. A diaphragm is arranged in the region of issue of the line into the passenger space, and a throttle valve adjustable in dependence on an accelerator pedal is arranged between the diaphragm and the main line.
DE 44 35 296 A1 describes a motor vehicle with an internal combustion engine, in which the arrangement known from DE 42 33 252 C1 is to be improved. For this purpose, a line pipe, which is provided with at least one acoustic resonator, adjoins the diaphragm on the side facing away from the pipe piece.
Particularly with regard to supercharged internal combustion engines, that is to say in internal combustion engines with turbochargers or compressors, however, there is a problem that, in particular, in the line leading from the intake line to the diaphragm, such high pressures prevail that the diaphragm is exposed to a very high static preload which not only impairs the functioning of the diaphragm for the transmission of sound waves, since the diaphragm experiences excessive deflection, but may also lead to a load on the diaphragm such that damage to the latter during operation cannot be ruled out. A further disadvantage of the known prior art is that the sound pattern transmitted, for example, to the interior can be influenced only slightly.
An object of the present invention, therefore, is to provide a device for noise configuration in a motor vehicle, which, in particular, is also suitable, without any difficulty, for supercharged internal combustion engines. However, such a device is preferably also to be suitable for non-supercharged internal combustion engines and, furthermore, is to make it possible to influence simply, and in as wide-ranging a way as possible, the sound pattern which emanates from the internal combustion engine and is to be appropriately transmitted.
This object is achieved, according to the invention, by providing a device for noise configuration in a motor vehicle, with at least one hollow body which is divided into at least two spaces, one space being connected to a gas-carrying part of an internal combustion engine arranged in the motor vehicle, and the other space being coupled acoustically to at least one of an interior of the motor vehicle, an engine space of the motor vehicle, and a space surrounding the motor vehicle, wherein the hollow body is divided into two spaces by an essentially acoustically inactive wall, and wherein a vibrational element which extends into both spaces is arranged within the hollow body.
According to the invention, the hollow body is divided into the two spaces by an essentially acoustically inactive wall. By means of this wall, which therefore transmits essentially no sound waves from the space connected to the gas-carrying part into the space which is coupled acoustically to the interior and/or to the engine space and/or to the space surrounding the motor vehicle, a separation of the two spaces of the hollow body from one another is provided, which can be exposed without difficulty to pressure load even in the case of supercharged internal combustion engines. It is now possible, even in the case of supercharged internal combustion engines, to connect the hollow body directly upstream of the throttle valve, with the result that the sound character which is often unfavorable because of flow noises and low sound-pressure levels when the hollow bodies are connected to the air filter can be avoided.
The wall according to the invention may be designed to be so rigid that it can easily cope with the pressure loads which occur. The appropriate selection of the wall depends on the respective application.
The vibrational element which, according to the invention, extends into both spaces is provided for transmitting the sound waves from the space connected to the gas-carrying part into the space coupled acoustically to the interior. Thus, the noises occurring in the region of the internal combustion engine are therefore transmitted to the interior and/or the engine space and/or to the space surrounding the motor vehicle, so that the driver can detect acoustically the load-dependent impression of noise of the internal combustion engine.
By the sound-wave transmission being uncoupled according to the invention from the separation of the two spaces, a multiplicity of possibilities for designing the vibrational element are afforded, thus entailing the advantage that the device according to the invention can be used for the most diverse internal combustion engines, the most diverse motor vehicles and the most diverse areas of application. The sound issuing from the hollow body may advantageously be guided into the interior, the engine space or else outwards.
Advantageously, it is not necessary to increase the external sound level, with the result that the exhaust system can be sound-insulated as effectively as possible, thus leading to a considerable relief of the environment and of the adjacent surroundings of the motor vehicle. The setting of the interior noise is uncoupled from the external noise.
It is possible, moreover, to insulate the interior of the motor vehicle from disturbing external noises, such as wind noises or rolling noises of the vehicle wheels, since these noises, usually felt to be unpleasant by the driver, but hitherto necessary for the driver""s acoustic orientation, can now be as far as possible kept away from the interior, since, with the aid of the device according to the invention, the information on the load state of the internal combustion engine can be absorbed by the driver in a way which is felt to be as pleasant as possible.
In an advantageous development of the invention, the vibrational element can divide the two spaces in each case into subspaces, at least the subspaces of the space connected to the gas-carrying part being connected to one another in order to allow pressure compensation.
When the vibrational element thus ensures a further subdivision of the two spaces, this allows even better transmission or higher amplification of the sound waves emanating from the internal combustion engine, so that the effectiveness of the device according to the invention is increased. In this respect, the necessary pressure compensation is afforded by a connection of at least the subspaces of the space connected to the gas-carrying part.
In further embodiments, this connection may be formed, for example, by a bore or by a duct.
When, in another advantageous design of the invention, in which another hollow space is arranged in the line leading to the interior and/or to the engine space of the motor vehicle and/or to the space surrounding the motor vehicle, wherein at the entrance an absorption material is arranged in the hollow body so, through the appropriate design of the hollow body and the absorption material, a reduction of the high-frequency portions and simultaneously an amplification of the low-frequency portions of the transmitted sounds is possible.
This design could also be used if the vibrational element were only designed as a membrane and if no acoustically inactive wall were provided.